Two senior Tories have increased tensions on the coalition government after they suggested reform of the House of Lords was a low priority.

Philip Hammond, the defence secretary, warned on Sunday that the reform should not be a central issue for the coalition's legislative programme. And, in what appeared to be a co-ordinated attack, Lady Warsi, the Conservative party co-chair, said changes to the upper house should not be the government's focus.

Their comments will not be received warmly by Liberal Democrat colleagues, who have made clear that they expect the constitutional reform to be pushed through. It is a flagship project of the party's leader, Nick Clegg.

Appearing on BBC1's The Andrew Marr show, Hammond warned that the public would want the government to focus on "the things that matter", rather than Lords reform. He said: "Legislation on the House of Lords is in the Queen's speech. It will be introduced, and it will proceed. The question will be to what extent the government should be prepared to clear the decks of everything else in order to possibly deal with a lengthy and very complex war of attrition over this particular piece of legislation."

Asked on Sky News's Murnaghan programme about the reform, Warsi said: "Do I feel that the House of Lords reform is an absolute priority right now? No I don't. I have knocked on many, many doors recently and not one person has said that it is their priority."

Lord Owen, a former foreign secretary and co-founder of the Social Democratic party, attacked the reforms as "cack-handed" and a "farce". In an interview with the Sunday Telegraph, he called for change but criticised the "childish" way in which the Tories and Lib Dems have used the issue as a bargaining tool between them. He fears the reforms will descend into a "monumental Lord Ashdown, a former Lib Dem leader, hit back at the weekend, declaring that it should be a priority to make the Lords partially elected. "Lets make this clear. We expect to see it through," he told Sky.

The chancellor, George Osborne, has previously hinted that the government would be willing to compromise on Lords reform if the bill started to clog up the parliamentary timetable.

"Parliament can discuss these issues. Parliament's very good at discussing constitutional issues," he said. "But it is not going to be occupying the bulk of the time of people like myself, David Cameron, and indeed Nick Clegg."